1. Field of Invention
This invention relates to a braking torque control system for a wheeled vehicle that has a regenerative braking torque generator and a frictional braking torque generator.
2. Description of Related Art
Braking systems having a regenerative braking torque generator and a frictional braking torque generator are known. A regenerative braking torque generator gives wheels regenerative braking torque, for example, by regenerative brake action of an electric motor connected to the wheels. A frictional braking torque generator gives wheels frictional braking torque, for example, by pressing friction devices on brake rotors rotating with the wheels. An example of such a braking torque control system is disclosed in Japanese Laid-Open Patent Application No. 7-205800. This system has a regenerative braking torque generator and a hydraulic braking torque controller that functions as a frictional braking torque generator. This system generates target total braking torque on the basis of exchanging data between the regenerative braking torque generator and the hydraulic braking torque controller. In this system, when the regenerative braking torque generator fails, the regenerative braking torque is controlled to zero and the hydraulic braking torque is controlled to the target total braking torque. This system does not describe any method of controlling the system when there is a failure of the exchanging of data between the regenerative braking torque generator and the hydraulic braking torque controller.